What’s the difference between popular and scholarly/peer-reviewed articles?

From Guides

Articles published in magazines (e.g., Newsweek, The Economist, The Nation) and newspapers are considered popular because they are written for a general audience by journalists rather than scholars in the field and are not peer reviewed. Articles published in academic, peer-reviewed journals are written by scholars in the field and are most often reviewed by other scholars before being published. See Articles Overview for more information.